1. Field of the Invention
The present invention relates to an axle box suspension for supporting the axle of a truck by means of an axle anchor rod integrally formed with the axle box and operatively connected to a truck frame of a railway vehicle or car or the like.
2. Description of the Prior Art
An axle anchor rod type axle box suspension for mounting the axle of a railway vehicle upon a truck frame is already disclosed, for example, in Japanese Patent Laid-Open No. 58-63568 and No. 58-118447. FIGS. 10A and 10B show such conventional examples. In the drawings, numeral 13 denotes a wheel, which is mounted upon the same axle as that of a wheel (not shown) provided at the opposite side of the vehicle. Two axles are mounted within the vicinity of both ends of a truck frame 12, thereby constituting one truck. Numeral 3 denotes an axle box which contains a bearing 2 and the like for the axle 1. Extending from the right side of the axle box 3 is an axle anchor rod 3' formed integrally with the axle box and rotatably slidably supported by means of a pin 8', having a resilient element 7a wound therearound, with respect to the truck frame 12. Extending from the left side of the axle box 3 is one end of a link 11 which is connected thereto by means of a pin 10, and the other end of the link 11 is coupled to the truck frame 12 through means of a resilient element 7b. Numeral 6 denotes an axle spring, which buffers relative upward and downward movements between the truck frame 12 and the axle 1.
In accordance with this axle box suspension, the upward and downward vibrations which occur between the truck frame 12 and the wheel 13 are permitted to occur by means of the rotatably sliding pins 8' and 10.
The axle anchor rod type axle box suspension shown in FIGS. 11A and 11B eliminates a sliding section and is seen to include an axle anchor rod 3' which is coupled to a truck frame 12 by means of a pin 8' having a resilient element 7a wound therearound. Since the axle anchor rod 3' comprises a cantilever beam having forked or laterally separated ends, two sets of resilient elements 7a and pins 8' must be provided as shown in FIG. 11B so as to resist any external force applied in the axial direction.
Furthermore, in order to prevent any reduction in the wheel load (or a derailment caused at its final stage of the reduction) due to an external force in the axial direction or an irregularity of the tracks of the rails, a resilient bearing supporting element 7c is annularly interposed between a bearing 2, the axle box 3, and a bearing retainer 5.
The performance required for a modern railway vehicle includes high speed running performance, easiness of maintenance and a reduction in the vehicle weight so as to reduce the amount of damage imposed upon the rails, and the like.
However, as will be appreciated from the conventional example in FIGS. 10A and 10B of the prior art, when the vehicle is coasting, the act of absorbing a vibration in the axial direction of the vehicle is deteriorated due to sliding movements and gaps defined between the pin 8' and the resilient element 7a, between the pin 8' and the truck frame 12, and between the pin 10 and the link 11, so that the running stability of the vehicle is reduced, whereby the running ability at high speed is also greatly reduced. Furthermore, additional problems occur, such as, for example, deterioration in the running performance of the vehicle due to the aging wear of the slide sections and the gap sections and complication in its maintenance due to lubrication and replacement of the components thereof.
On the other hand, in the conventional example shown in FIGS. 11A and 11B, the slides and gaps do not exist within the axle box suspension, but its axle anchor rod is increased in size and in weight, and the space required for mounting the same is increased. Furthermore, as shown in a sectional view of the axle anchor rod 3' in FIG. 12, since the axle anchor rod 3' has a large twisting rigidity in the rotating direction I, (that is, in the running direction) and a large width dimension in the axial direction of the resilient elements 7a, the twisting rigidity between the axle anchor rod 3' and the truck frame 12 is large. Accordingly, it is necessary to in fact provide the resilient element 7c in conjunction with the bearing 2 so as to prevent a reduction of the wheel load (or a derailment) which is possibly caused when the track is twisted due to an irregularity in the track or a reduction in the cant (the difference between the heights of an inside rail and an outside rail along a curve), whereby problems such as, for example, a complicated construction and an increase in the weight of the axle box 3 are caused.